In Situ Rapid Formation of a Nickel–Iron-Based Electrocatalyst for Water Oxidation
journal contributionposted on 09.09.2016, 00:00 by Jianying Wang, LvLv Ji, Zuofeng Chen
If an oxygen evolution reaction (OER) catalyst is expected to be more durable, especially under conditions of thin-layer catalysts or strong gas evolution, it will ideally function in a self-repair mode. In earlier studies, the electrochemical fabrications of Ni–Fe oxide catalysts were exclusively carried out by cathodic reduction of Ni(II) and Fe(III,II) in an individual solution that is different from the alkaline media commonly used for the OER. The procedure does not suggest that the dissolution/corrosion of the film catalysts could be countered by continual catalyst formation during the OER. Herein, we report a highly active NiFeOx catalyst by in situ rapid (3–15 min) anodic deposition of Ni(II) and Fe(III,II) in concentrated carbonate solution. At a transparent indium tin oxide (ITO) electrode, the conformal deposition of NiFeOx (7–11-atom layer) results in a very low optical loss (5–8%) with activity comparable to that of other planar NiFeOx films. Extension to a 3D nickel foam produces a hierarchical coating of grasslike structure. With few added Ni(II) and Fe(III) atoms to counter the film dissolution/corrosion, the catalyst can deliver a stable current density of 100 mA/cm2 at an overpotential of only 260 mV in alkaline media. This example of a NiFeOx catalyst forms during in situ OER and operates by a self-repair mode, highlighting a truly important feature for the practical application of this state of the art OER electrocatalyst.